More than 1.5 million subscribers have signed up for MMORPG World of Warcraft, according to developer Blizzard Entertainment, but stock shortages of the game continue to afflict UK retailers. The game was released in North America last November and has since enjoyed successful launches in Korea and Europe, with the highest number of players online at one time topping 500,000.

"All of us at Blizzard are extremely gratified and amazed at the international demand for World of Warcraft," said Blizzard president Mike Morhaime. "From region to region, we've seen a phenomenal level of enthusiam for WoW, and we're absolutely thrilled people are enjoying the game so much."

Demand for World of Warcraft in the US was so great that restrictions had to be placed on the number of copies sent to retail in order to avoid server overload, and players continue to report problems with logging in to popular game servers. It's not known whether or not the same restrictions were applied in Europe, but the game is currently sold out in UK high street and online stores, with further stock not expected to arrive until later this month.